Did my Monferno's Hidden Power just... change when it evolved?

Question

So in Platinum, I newly taught my Monferno Hidden Power... Water. Then I evolved it and now its showing my Hidden Power Ground. I haven't used any hack. No cheats. What happened?

Comments

How do you know it was HP Water before, and HP Ground now?
Did you check with the man in Veilstone Game Corner?

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When he has Hidden Power, you can see.

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You don't see what HP it is in battle, if that's what you mean.

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Really? Oh...

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You see what type the hidden power is on Pokemon Online and Showdown, but in game it will always appear as Normal type.

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As Hex said, I checked. I know its HP Water. 100%.

Answer 1

Are you using a ROM? Because Hidden Power type is based soley on IVs, and those dont change through evolution. If you are using a ROM there might be a glitch. And are you 100% sure it was water? Anyway, there was probably a glitch in your game if this happened.

Comments

Thanks!

Answer 2

Hidden Power is based on IVs. Did you lower your Monferno's IVs or someting. For further explanation visit: http://bulbapedia.bulbagarden.net/wiki/Hidden_Power_calculation